Alkalies for single powder photographic developers



as a mixture in a hermetically sealed package.

j 1 ALKALIES non SINGLE "POWDER PHOTO:

-GRAPHIC-DEVELOPERS 7 Ralph fiaxendlalm -Rochester, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation f New Jersey t 1N0 Drawing. pplication July 1 8, 1956 7 Serial'No.'. 5918,,526 V This invention relates to photographic developer compositions,.=the components of=which ,are mutually com:

patible and can therefore be packaged for merchandising These photographic developer mixtures are commonly termed single powder photographic developers, and the present invention more particularly relates a to single powder,

developers containing one or more alkali hydroxides which have been treatedv to lessen or to prevent their reactivity with components of the atmosphere as well as with other components of singlepowder developers.

This invention alsorelates to methods of treatin'galkali hydroxides with one or more protestant compounds to lessen or to prevent interaction of the alkali hydroxide ,withthe atmosphere, or with ,organic developing agents, as well as .to the treated alkaliproducts produced thereby.

. In the past, photographic developer powders have been packaged so that the developing agents are separated L from contact with the alkaline components to prevent interaction vtherebetween. More recently it has been found .that some developer mixtures may be protected by the addition of certain protectants so that the developingagents may be mixed directly with other components of the developer and the resulting developer mixture can be packaged .as .a single powder developer.

. Singlepowderdevelopers may.contain; for example, an organic developing agent such as monomethyl p-aminophenol sulfate, hydroquinone, p-aminophenol hydrochloride, p-aminophenol sulfate, pyrogallol, p-hydroxyphenyl glycine, catechol, diaminophenol hydrochloride, l-phenyl V 4-.methyl-3 pyrazolidone, 1 phenyl 4,4-dimethyl-3-pyraz-" olidone and suitable mixtures thereof, stable alkaline butter salts such as sodium carbonatewmonohydrate,

sodium -metaborate tetrahydrate (Na B O -4H O) and sodium .tetraborate pentahydrate (Na B O -5H O); and protectants such as boric anhydride, .metaboric acid, phthalic anhydride and sodium or potassium bisulfites and metabisulfitesand may also contain theyother well known ,ingredientsnormally present in a developer such as s odium-sulfite and potassium bromide, the normal and known-function of the alkali sulfite' being that of preservative, lessening the oxidation in solution of the organicdeveloping agent, while the known function of "potassium bromide is that of a restrainer particularly inhibiting fqg formation in the development of thesilver image. a i

, l-lowever when .employing sodium o'r-potassium .hy-

droxide .ir1,..such protected single powder mixtures, the

strongly hygroscopic nature of, sodium hydroxide. and

' 1 thedarnpness of itssurface has frequently been found to be the-cause of discoloration even in the presence of the above named protectants, "This is particularly disadvantageous since it is often ,desirableto [add a strong alkali such as sodium hydroxidetoadeveloperpowder to} give aihigli'er total"alkalinity,'or to add such strong alkali 'to' single powder 'mixture'sito" overcome the acidity introduced bythe" r'ot'e'c'tants i" and do'notcause caking of the mixture, s 1 The present invention will be further'illustrated in thev Ph'tented 'July 15,

of treating such alkali hydroxides to reduce their hygroscopic properties. i v a Yet another object is to provide a method of coating particles of alkali hydroxides with a 'nonhygroscopic coating which is also substantially inert in the presence of components of a single powder photographic developer,

Another object of this invention is to provide anoncaking sodium and potassium hydroxide having a coating thereon which is generated by a reaction between the selected alkali and an amide." e p Another object of this invention is to provide single powder photographic :developers containing sodium 1 or potassium'hydroxide which have been coated in accord ancewiththe present invention :with the reaction product Y of the selected alkali and an amide.

Other objects will appear hereinafter.

In accordance with .a feature of the present invention these and other objects are attained by forminga coating on the selected jalkali hydroxide by heating in the presence of an amide 'to a temperature until ammonia is produced as a byproduct. The ammonia being very volatile is easily expelled from the now coated alkali with which'it does not react.

T he preferred treatment involves employing an-alkali hydroxide in particle form and an amide which on heat- 1 Suitable ing will produce ammonia .as a byproduct. amides include urea, formarnide, acetamide, propionamide,lbenzamide, phthalamide', oxamide. 'These form the corresponding alkali salts, theacetate, propionate, etc. Generally, weighed amounts of the reactants are employed. 'The reaction may ;be conducted in 'a rotary. blender in atemperature' range of to 108 C. -for approximately 60 minutes. i is suitably'removed from the reaction mixture. If desired, higher temperatures above 108 C., for example 1 20'to C., may be employed to increaserthe rate ofreaction. f I 1 The resulting product comprises an alkali hydroxide core having an adherent coating thereon and when this coated product vis exposed to'atmospheric conditions; it v is found that the rate of moisture pick-up is very much atmosphericpconditions, whereas untreated alkalies become very damp after short exposure and eventually dissolve in the water which'they absorb. The treated compounds can be packed in the soda portion of photographic developers withoutcausing caking. When added to single powder photographic developer mixtures the treated compounds retard deterioration ofthel mixture followingexamplesz t 7 Example 1 A l-kilogram lot' of powered sodium hydrbxide was blended with 7.5 grams of ilreaiand thernixture, in a rotary blender, was heated for 6 0 minutes in the temperature range of'90'to 108 CI The productfwals frr from .the dustiness and showed good handling properties.- The thus coated sodiumfhydroxide was employed in a- The by-pr'oduct, ammonia,

agents was noted.

single powder developer containing Elon (I -methylaminophenol sulfate) 2.5 grams, hydroquinone 5.0 grams, sodium sulfite 25.0 grams, borax 25.6 grams, potassium bromide 1.8 grams, and boric anhydride 1.3 grams and incubated at 120 F. for three weeks. No evidence of discoloration, which would indicate a reaction between the sodium hydroxide and one or more of the developing Example 2 l The coated sodium hydroxide of Example 1 was again mixed with 7.5 grams of urea and heated for 60 minutes in the temperature range of 90 to 108 C. This double treated product which exhibited no tendency to cake, was added to the same type of single powder developer as shown in Example 1, the amounts of the components being the same as in Example 1. No evidence of discoloration of the single powder developer was noted after'6 months incubation at 120 F.

Example 3 Sufficient formamide to react with 1% of the sodium hydroxide was placed together with the sodium hydroxide in aflask. An exothermic reaction was found to proceed rapidly.- This coated sodium hydroxide was added to the same type of single powder developer as described in Example 1, the amounts of the components being the same as in Example 1. The single powder mixture did not discolor after several months incubation at 120 F.

Example 5 Following the treatment with urea, as described in Example 1, the sodium hydroxide was then treated with dimethyl phthalate under the same conditions of mixing and temperature as in the case of treating with urea. Alkali hydroxides receiving one treatment with urea and two with dimethyl phthalate proved highly resistant to prolonged incnbations when added to the developer powders as described above. was free flowing and relatively uniform in particle size.

Example 6 Examples 1 to 5 were repeated with potassium hydroxide and similar results were obtained.

Example 7 To illustrate further the use of the coated sodium hydroxide in photographic developer powder packing the following powder was prepared: 7

. Grams Sodium sulfite, desiccated 22.5 Sodium tetraborate pentahydrate 25.8 Potassium bromide 1.8 Sodium hydroxide-urea treated 3.5

This mixtureQwhich represents the salt portion of a photographic developer powder remained free flowing after storage of 6 weeks at 120 C. A similar powder in which untreated sodium hydroxide was used caked severely when stored under the same conditions.

Example 8 This example further illustrates the use of potassium hydroxide which has been treated with formamide in a The sodium hydroxide obtained I single powder mixture. The following single powder When incubated at 120 C., this single powder mixture had no tendency to discolor or to deteriorate. A similar formula using untreated potassium hydroxide was unusable after the same incubation treatment.

Since the by-product in'the reaction between the alkali hydroxide and the amide is ammonia which, at the temperature of the reaction, is expelled from the product, my present invention has a decided advantage over other processes for treating alkali hydroxides wherein water or an alcohol by-product remains with the product.

I claim:

1. The method of forming a non-hygroscopic coating on an alkali hydroxide which comprises heating the hydroxide with an amide'selected from the group consisting of urea, formamide and phthalamide to form a thin coating of the reaction product of the hydroxide and the selected amide on the alkali hydroxide, and expelling the ammonia formed during the reaction.

2. The method of forming a non-hygroscopic coating on an alkali hydroxide selected from the group consisting of sodium and potassium hydroxide which comprises mixing the selected alkali hydroxide in comminuted form with an amide selected from the group consisting of urea, formamide and phthalamide and heating the mixture at a temperature to promote the formation of an integral non-hygroscopic coating of the reaction product of the hydroxide and the selected amide on the surface of the said alkali hydroxide and the expulsion of ammonia therefrom.

3. A stable single powder photographic developer composition which resists deterioration when heated to 120 F. containing an organic silver halide developer, a basic ingredient selected from the group consisting of alkali borates and sulfites and an alkali hydroxide selected from the group consisting of sodium and potassium hydroxide having a protective coating thereon of the reaction product of the selected alkali hydroxide and an amide selected from the group consisting of urea, formamide and phthalamide.

4. An alkali hydroxide having a coating thereon of the reaction product of the alkali hydroxide and an amide 7 selected from the group consisting of urea, formamide and phthalamide.

5. Sodium hydroxide having a coating thereon of the reaction product of sodium hydroxide and an amide selected from the group consisting of urea, formamide and phthalamide.

6. Potassium hydroxide having a coating thereon of the reaction product of potassium hydroxide and an amide selected from the group consisting of urea, formamide and phthalamide. 7. Sodium hydroxide having a coating thereon of the reaction product of sodium hydroxide and urea.

8. Sodium hydroxide having a coating thereon of the reaction productof sodium hydroxide and formamide.

9. Sodium hydroxide having a coating thereon of the reaction product of sodium hydroxide and phthalamide.

References Cited in the file of this patent UNITED STATES PATENTS 150,509 Babbitt May 5, 1874 270,998 Taylor Jan. 23, 1883 2,532,201 'Sprague' Nov. 28, 1950 2,639,221 Henn May 19, 1953 

3. A STABLE SINGLE POWDER PHOTOGRAPHIC DEVELOPER COMPOSITION WHICH RESISTS DETERIORATION WHEN HEATED TO 120* F. CONTAINING AN ORGANIC SILVER HALIDE DEVELOPER, A BASIC INGREDIENT SELECTED FROM THE GROUP CONSISTING OF ALKALI BORATES AND SULFITES AND AN ALKALI HYDROXIDE SELECTED FROM THE GROUP CONSISTING OF SODIUM AND POTASSIUM HYDROXIDE HAVING A PROTECTIVE COATING THEREON OF THE REACTION PRODUCT OF THE SELECTED ALKALI HYDROXIDE AND AN AMIDE SELECTED FROM THE GROUP CONSISTING OF UREA, FORMAMIDE AND PHTHALAMIDE. 